The present invention relates to a floppy disk drive apparatus capable of using both high- and low-density disks.
When data is to be recorded on a disk, the recording density depends on the gap length of the read/write head. More specifically, as the gap length is elongated, the disk is deeply magnetized. However, the resolution is decreased, and hence it is not desirable for a read/write operation in a high-density recording disk. On the other hand, as the gap length is shortened, the depth of magnetization becomes shallow, thereby degrading the overwrite characteristic. For this reason, it is not desirable for a read/write operation in a low-density disk. Accordingly, a disk to be used is selected on the basis of the gap length of the read/write head. However, a floppy disk drive apparatus must have compatibility with both high- and low-density disks.
In a conventional floppy disk drive apparatus, a magnetic head using a tunnel erase system is often used. Generally, in this system, data written in a recording area is erased by overwrite. If data is written on a disk, which has been used in a floppy disk drive apparatus including a read/write head having a long gap length, using a drive apparatus for high-density recording, i.e., including a read/write head having a short gap length, the surface of the disk is magnetized by the newly written data. However, residual magnetization is present in a deep portion of the disk. As a result, the overwrite characteristic is degraded, and hence low- and high-density recording cannot be performed by a single apparatus.